US 6,995,558 B2Granted

System and method for characterizing a sample by low-frequency spectra

AssigneeWavBank, Inc.

InventorsBennett M. Butters, Patrick Naughton, Michael Leonard

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Abstract

A method and apparatus for interrogating a sample that exhibits molecular rotation includes placing the sample in a container having both magnetic and electromagnetic shielding, where Gaussian noise is injected into the sample. An electromagnetic time-domain signal composed of sample source radiation superimposed on the injected Guassian noise is detected, and this signal is used to generate a spectral plot that displays, at a selected power setting of the Gaussian noise source, low-frequency spectral components characteristic of the sample in a selected frequency range between DC and 50 kHz. In one embodiment, the spectral plot that is generated is a histogram of stochastic resonance events over the selected frequency range. From this spectrum, one or more low-frequency signal components that are characteristic of the sample being interrogated are identified.

Claims14

Dependent claims

Apparatus for interrogating a sample that exhibits low-frequency molecular motion, comprising:

a container adapted for receiving the sample, the container having both magnetic and electromagnetic shielding;
an adjustable-power source of Gaussian noise for directing Gaussian noise to the sample, with the sample in the container;
a detector for detecting an electromagnetic time-domain signal composed of sample source radiation superimposed with the directed Gaussian noise;
and
an electronic computer adapted to receive the time-domain signal from the detector, and to process the signal to generate a spectral plot that displays, at a selected power setting of the Gaussian noise source, low-frequency spectral components characteristic of the sample in a selected frequency range between DC and 50 kHz, wherein the electronic computer includes machine readable code operable to:
(i) store the time-domain signal of the sample over a sample-duration time T;
(ii) select a sampling rate F for sampling the time domain signal, where F*T is a total sample count S, F is approximately twice a frequency domain resolution f of a Real Fast Fourier Transform of the time-domain signal sampled at sampling rate F, and S>f*n, where n is at least 10,
(iii) select S/n samples from the stored time domain signal and perform a Real Fast Fourier Transform (RFFT) on the selected samples to produce an RFFT signal,
(iv) normalize the RFFT signal and calculate an average power for the RFFT signal,
(v) place an event count in each of f selected-frequency event bins where a measured power at a corresponding selected frequency is greater than an average power times a value ε, where 0<ε<1 and is chosen such that a total number of counts placed in an event bin is between about 20–50% of a maximum possible bin counts in that bin,
(vi) repeat steps (iii–v), and
(vii) generate a histogram that shows, for each event bin f over a selected frequency range, a number of event counts in each bin.

9 more elements

A method for interrogating a sample that exhibits low-frequency molecular motion, comprising:

placing the sample in a container having both magnetic and electromagnetic shielding,
injecting noise into the sample at a selected noise amplitude;
recording an electromagnetic time-domain signal composed of sample source radiation superimposed on the injected noise,
generating a spectral plot that contains, at a selected power setting of the noise source, low-frequency, sample-dependent spectral components characteristic of the sample in a selected frequency range between 100 and 50 kHz, and
repeating the injecting, recording and generating at different selected noise amplitudes until a plot showing a maximum or near maximum number of spectral components characteristic of the sample is generated,
wherein the generating includes (i) calculating a series of Fourier spectra of the time-domain signal over each of a plurality of defined time periods, in a selected frequency range between 100 Hz and 50 kHz, and (ii) averaging the Fourier spectra, and
wherein the calculating includes:
(i) storing a time-domain signal of the sample over a sample-duration time T;
(ii) selecting a sampling rate F for sampling the time-domain signal, where F*T is a total sample count S, F is approximately twice a frequency domain resolution f of a Real Fast Fourier Transform of the time-domain signal sampled at the sampling rate F, and S>f*n, where n is at least 10,
(iii) selecting S/n samples from the stored time-domain signal and performing a Real Fast Fourier Transform (RFFT) on the selected samples to produce an RFFT signal,
(iv) normalizing the RFFT signal and calculating an average power for the RFFT signal,
(v) placing an event count in each of f selected-frequency event bins where a measured power at a corresponding selected frequency<average power *ε, where 0<ε<1 and is chosen such that a total number of counts placed in an event bin is between about 20–50% of a maximum possible bin count in that bin,
(vi) repeating (iii) through (v), and
(vii) generating a histogram that shows, for each event bin f over a selected frequency range, a number of event counts in each bin.

11 more elements

A method for interrogating a sample that exhibits low-frequency molecular motion, comprising:

receiving the sample;
magnetically and electromagnetically shielding the sample;
directing adjustable-power Gaussian noise to the sample;
detecting an electromagnetic time-domain signal composed of sample source radiation superimposed with the directed Gaussian noise;
and
receiving the time-domain signal, and processing the signal to generate a spectral plot that displays, at a selected power setting of the Gaussian noise source, low-frequency spectral components characteristic of the sample in a selected frequency range between DC and 50 kHz,
wherein the processing includes:
(i) storing the time-domain signal of the sample over a sample-duration time T;
(ii) selecting a sampling rate F for sampling the time domain signal, where F*T is a total sample count S, F is approximately twice a frequency domain resolution f of a Real Fast Fourier Transform of the time-domain signal sampled at sampling rate F, and S>f*n, where n is at least 10;
(iii) selecting S/n samples from the stored time domain signal and performing a Real Fast Fourier Transform (RFFT) on the selected samples to produce an RFFT signal;
(iv) normalizing the RFFT signal and calculating an average power for the RFFT signal;
(v) placing an event count in each of f selected-frequency event bins where a measured power at a corresponding selected frequency is greater than an average power times a value ε, where 0<ε<1 and is chosen such that a total number of counts placed in an event bin is between about 20–50% of a maximum possible bin counts in that bin;
(vi) repeating (iii)–(v);
and,
(vii) generating a histogram that shows, for each event bin f over a selected frequency range, a number of event counts in each bin.

12 more elements

An apparatus for interrogating a sample that exhibits low-frequency molecular motion, comprising:

means for placing the sample in a container having both magnetic and electromagnetic shielding;
means for injecting noise into the sample at a selected noise amplitude;
means for recording an electromagnetic time-domain signal composed of sample source radiation superimposed on the injected noise;
means for generating a spectral plot that contains, at a selected power setting of the noise source, low-frequency, sample-dependent spectral components characteristic of the sample in a selected frequency range between 100 and 50 kHz;
and,
means for repeating the injecting, recording and generating at different selected noise amplitudes until a plot showing a maximum or near maximum number of spectral components characteristic of the sample is generated,
wherein the means for generating includes means for calculating a series of Fourier spectra of the time-domain signal over each of a plurality of defined time periods, in a selected frequency range between 100 Hz and 50 kHz, and means for averaging the Fourier spectra, and
wherein the means for calculating includes:
(i) means for storing a time-domain signal of the sample over a sample-duration time T;
(ii) means for selecting a sampling rate F for sampling the time-domain signal, where F*T is a total sample count S, F is approximately twice a frequency domain resolution f of a Real Fast Fourier Transform of the time-domain signal sampled at the sampling rate F, and S>f*n, where n is at least 10;
(iii) means for selecting S/n samples from the stored time-domain signal and performing a Real Fast Fourier Transform (RFFT) on the selected samples to produce an RFFT signal;
(iv) means for normalizing the RFFT signal and calculating an average power for the RFFT signal;
(v) means for placing an event count in each of f selected-frequency event bins where a measured power at a corresponding selected frequency>average power*ε, where 0<ε<1 and is chosen such that a total number of counts placed in an event bin is between about 20–50% of a maximum possible bin count in that bin;
(vi) means for repeating the selecting, normalizing, and placing;
and,
(vii) means for generating a histogram that shows, for each event bin f over a selected frequency range, a number of event counts in each bin.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/683,875Filed 9 Oct 2003 · continuation in part
Priority: 29 Mar 2002
Published: US 2004/0183530 A123 Sep 2004
Granted: 7 Feb 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01N 37/005
Details not covered by any other group of this subclass: measurement methods not based on established scientific theories
G01R 33/032
Measuring direction or magnitude of magnetic fields or magnetic flux: using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
G01N
Investigating or analysing materials by determining their chemical or physical properties
G01R
Measuring electric variables

Family

Application10/112,927Parent of this continuation-in-part · filed 29 Mar 2002
PCT/US03/09544Parent of this continuation-in-part · filed 28 Mar 2003
PCT/US03/11834Parent of this continuation-in-part · filed 18 Apr 2003
US 2004/0183530 A1Pre-grant publication · published 23 Sep 2004
US 6,724,188 B2Parent of this continuation-in-part
US 2003/0184289 A1Published application
US 6,995,558 B2This patent

From the US filing history. Foreign family members aren’t listed.